GPIO management is pretty simple and is part of the same IP than the pin
controller for the Armada 37xx SoCs.  This patch adds the GPIO support to
the pinctrl-armada-37xx.c file, it also allows sharing common functions
between the gpiolib and the pinctrl drivers.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>